Chapter 11, 12, & 13 Review

In which of the following ways do plant hormones differ from hormones in animals? a. Plant hormones may travel through the air as a gas. b. Plant hormones function as only paracrine signals. c. Plant hormones typically travel from the hormone producing cell to an adjacent responding cell through gap junctions. d. Plant hormones may be transported from the hormone producing cell to the responding cell through a vascular system.

a. Plant hormones may travel through the air as a gas.

Which of the following statements best describes how steroid hormones access their receptors within target cells? a. Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell and nuclear membranes. b. Both steroid hormones and their receptors are produced by the same cells. c. Steroid hormones first bind to a steroid activator and this complex is transported across the cell membrane by a steroid transport protein. d. Steroid hormone receptors undergo conformational changes that relocate them on the membrane surface.

a. Steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell and nuclear membranes.

Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence? a. The cells show characteristics of tumors. b. The cells are unable to form spindle microtubules. c. The cells have nonfunctional MPF. d. The cells follow an altered series of cell cycle phases.

a. The cells show characteristics of tumors.

Which of the following statements best describes a cleavage furrow? a. a groove in the plasma membrane between daughter nuclei b. the separation of divided prokaryotes c. the space that is created between two chromatids during anaphase d. a ring of vesicles forming a cell plate

a. a groove in the plasma membrane between daughter nuclei

During which of the following processes does independent assortment of chromosomes occur? a. in meiosis I only b. in mitosis and meiosis I c. in meiosis II only d. in mitosis and meiosis II

a. in meiosis I only

Independent assortment of chromosomes is a result of which of the following processes? a. the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I b. the random combinations of eggs and sperm during fertilization c. the random distribution of the sister chromatids to the two daughter cells during anaphase II d. the diverse combination of alleles that may be found within any given chromosome

a. the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

If the DNA content of a diploid cell is x in the G1 phase of the cell cycle and 2x at metaphase of meiosis I, then the DNA content of the same cell at metaphase of meiosis II will be a. x b. 2x c. 0.25x d. 0.5x

a. x

How do cancer cells differ from normal cells? a. Cancer cells trigger chromosomal changes in surrounding cells. b. Cancer cells may be immortal. c. Cultured cancer cells exhibit anchorage dependence.

b. Cancer cells may be immortal. (Cancer cells can go on dividing indefinitely in culture if they are given a continual supply of nutrients; in essence, they are "immortal." Read about HeLa cells.)

Which statement correctly distinguishes the roles of protein kinases and protein phosphatases in signal transduction pathways? a. Protein kinases are involved in signal transduction in unicellular eukaryotes such as yeast. Protein phosphatases are involved in signal transduction in multicellular eukaryotes. b. Protein kinases activate enzymes by phosphorylating or adding phosphate groups to them. Protein phosphatases dephosphorylate or remove phosphate groups from enzymes, including protein kinases. c. Protein kinases are more critical than protein phosphatases to signal transduction enzymes.

b. Protein kinases activate enzymes by phosphorylating or adding phosphate groups to them. Protein phosphatases dephosphorylate or remove phosphate groups from enzymes, including protein kinases.

Which of the following statements best describes what happens to MPF during mitosis? a. The Cdk component of MPF is degraded. b. The cyclin component of MPF is degraded. c. It is completely degraded. d. It is phosphorylated by a Cdk, which inactivates it.

b. The cyclin component of MPF is degraded.

What are the genetic or other changes that might cause cancer cells to escape normal cell cycle regulation? a. The underlying basis for this altered behavior is a series of genetic changes, including mutations in genes whose protein products normally code the enzymes of DNA replication. b. The underlying basis for this altered behavior is a series of genetic and cellular changes, including mutations in genes whose protein products normally regulate the cell cycle. These gene products are often proteins that function in cell signaling pathways. c. The underlying basis for this altered behavior is a series of cellular changes, including misfolding of proteins that function in cell signaling pathways. The incorrect folding of mutant proteins causes their incorrect work. d. The underlying basis for this altered behavior is a series of genetic and cellular changes, including mutations in genes whose protein products normally code the signaling enzymes. These gene products are often proteins that function in metabolic pathways.

b. The underlying basis for this altered behavior is a series of genetic and cellular changes, including mutations in genes whose protein products normally regulate the cell cycle. These gene products are often proteins that function in cell signaling pathways.

Which of the following statements best describes the effect of a mutation that alters the structure of the a factor so that it no longer binds to the corresponding receptor on α cells? a. The a cells will fail to initiate the shape changes necessary for mating after binding α factor. b. The α cells will fail to initiate the shape changes necessary for mating. c. The a cells will mate with other a cells rather than α cells. d. The α cells will fail to secrete the α factor.

b. The α cells will fail to initiate the shape changes necessary for mating.

For a species with a haploid number of 23 chromosomes, how many different combinations of maternal and paternal chromosomes are possible for the gametes based on the independent assortment of chromosomes during meiosis? a. 23 b. about 8 million c. 46 d. about 1,000

b. about 8 million

FtsZ is a bacterial protein that forms a contractile ring involved in binary fission. Its function is analogous to which of the following structures in eukaryotic cells? a. the mitotic spindle of eukaryotic cells b. the cleavage furrow of eukaryotic animal cells c. the microtubule-organizing center of eukaryotic cells d. the cell plate of eukaryotic plant cells

b. the cleavage furrow of eukaryotic animal cells

In a diploid cell with four chromosome pairs (2n = 8), how many sister chromatids will be found in a nucleus at prophase of mitosis? a. 32 b. 8 c. 16 d. 4

c. 16

Which of the following statements best describes how cytokinesis differs between plant and animal cells? a. The structural proteins of plant cells separate the two cells; in animal cells, a cell membrane separates the two daughter cells. b. The contractile filaments found in plant cells are structures composed of carbohydrates; the cleavage furrow in animal cells is composed of contractile proteins. c. Plant cells deposit vesicles containing cell wall building blocks on the metaphase plate; animal cells form a cleavage furrow. d. Cytokinesis occurs between metaphase and anaphase in plant cells; it occurs after anaphase in animal cells.

c. Plant cells deposit vesicles containing cell wall building blocks on the metaphase plate; animal cells form a cleavage furrow.

Which of the following statements describing kinetochores is correct? a. They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers b. They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis. c. They are sites at which microtubules attach to chromosomes. d. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow. e. They interdigitate at the cell's equator and then move apart, causing the cell to elongate.

c. They are sites at which microtubules attach to chromosomes. (As the spindle depolymerizes, the kinetochores appear to move along the spindle fiber, dragging the attached chromosomes with them.)

What number and types of chromosomes are found in a human somatic cell? a. n chromosomes b. 22 autosomes and 1 sex chromosome c. 45 autosomes and 1 sex chromosome d. 44 autosomes and 2 sex chromosomes e. 21 autosomes and 2 sex chromosomes

d. 44 autosomes and 2 sex chromosomes (Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males).)

A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain? See Concept 12.1 a. 46 b. 23 c. 46 or 92, depending on the portion of prophase examined d. 92 c. 23 or 26, depending on the portion of prophase examined

d. 92 (Mitosis follows the duplication of the cell's DNA.)

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? a. The cells have half the number of chromosomes and half the amount of DNA. b. The cells have half the amount of cytoplasm and twice the amount of DNA. c. The cells have the same number of chromosomes and half the amount of DNA. d. The cells have half the number of chromosomes and one-fourth the amount of DNA.

d. The cells have half the number of chromosomes and one-fourth the amount of DNA.

During which of the following processes do sister chromatids separate from each other? a. during meiosis I only b. during meiosis II only c. during both mitosis and meiosis I d. during both mitosis and meiosis II

d. during both mitosis and meiosis II

Many diploid organisms produce haploid gametes for reproduction. Which of the following best describes how the diploid number of chromosomes is restored in the offspring of these organisms? a. DNA replication creates homologous chromosomes b. independent assortment in meiosis allows random combinations of chromosomes c. synapsis during prophase of meiosis I creates random combinations of alleles d. fertilization combines chromosomes from each parent into resulting zygote

d. fertilization combines chromosomes from each parent into resulting zygote

Why is it difficult to observe individual chromosomes with a light microscope during interphase? a. sister chromatids do not pair up until division starts b. the spindle must move them to the metaphase plate before they become visible c. they leave the nucleus and are dispersed to other parts of the cell d. interphase chromosomes are long, thin strands unlike the condensed chromosomes visible in mitosis e. the DNA has not been replicated yet

d. interphase chromosomes are long, thin strands unlike the condensed chromosomes visible in mitosis (Except during the M phase, the DNA is extended, allowing its genes to be transcribed for protein synthesis.)

Binding of a growth factor to its receptor is most likely to immediately activate which of the following molecules? a. cAMP b. phosphorylase c. adenylyl cyclase d. protein kinase

d. protein kinase

What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other? a. the chromatin b. the cohesin c. the centrosome d. the centromere

d. the centromere